Arrangement for wireless signaling



- 27, 1938. E. KRAMAR ET AL 2,141,247

ARRANGEMENT FOR WIRELESS SIGNALING Filed May 14, 1936 m M 7 R2 F/ .3

Hece wer' r p g J f I l. p fizvezgi'arax J Ernst Krarmarr P 4 P Heinich-flrunsw/y 5 by I Patented Dec. 27, 1938 UNITE s'rrEs ARRANGEMENT FORWIRELESS SIGNALING Germany, a company Application May 14, 1936, SerialNo. 79,704

In Germany May 17, 1935 5 Claims.

In Patent 2,028,510, issued J anuary21, 1936, it is proposed in order toobtain course lines, to feed a dipole continuously from a high frequencygenerator and to key suitably erected reflectors. This patent alsospecifies that by providing for difierent distances between transmitterdipole and reflector dipole or dipoles, diiferent directionalcharacteristics are obtainable. It is also stated there that the lengthof the dipoles may be difierent within narrow limits. However thedirectional characteristics only give useful angles of intersection ifthe length of the transmitter dipole and of the reflector dipole isapproximately M2 and the distance between them approximately M4, A beingthe operative wavelength.

The invention has for its object to so develop this arrangement that thespatial dimensions thereof shall be considerably diminished. Thisrequirement, which for instance is to increase the safety of the traflicon landing grounds, is in accordance with the invention accomplished byreducing the spatial length of the reflector dipole or dipoles, ascompared with the electrical length, and by electrically elongating thereflector dipole or dipoles to tune over to the operative wavelength.The electrical length should be adjusted to M2, if unearthed dipoles areused, and M4 if earthed dipoles are employed.

The principle of the antenna arrangement itself need not be explainedmore fully. The arrangement shown in the said patent is altered in sucha manner that as stated the dimensions are diminished. The electricelongation of the reflector dipoles is accomplished preferably byinductances interposed in the current bulge or by other customary meansof elongation. Also the means of elongation may be common to a pair ofreflector dipoles, as will be understood from the following description,reference being had to the accompanying drawing in which- Figs. 1 and 2show diagrams of radiation obtained from experimental arrangementscomprising freely erected dipoles, Fig. 1 relating to the knownconstruction, Fig. 2 to the novel one. Fig. 3 is a schematic elevationof an embodiment of the present invention.

In Fig. 1 two diagrams of radiation 0, and b are represented which showthat by changing the length of the transmitter dipole there is obtainedonly a trifling variation of the radiation diagram. For the sake ofcompleteness it may be mentioned that in each case only the horizontaldiagram has been illustrated. With the diagrams a and b the distancebetween transmitter and reflector dipole was M14 and the length of thereflector dipole M2 (in spatial as well as in electrical relation). Inthe case of the diagram a. the length of the transmitter dipole amountsto M8, in the case of the diagram 1) to M3. While the spatial dimensionsof this antenna structure, it is true, are considerably diminished, theconfiguration of the diagram however is approximately the same, as areconsequently also the angles of intersection obtained in this way. As iswell known however, in order to increase the sensitivity of indication,the angles of intersection should be as acute'as possible.

If in accordance with the invention however the spatial length of thereflector dipole is diminished while at the same time an electricelongation to M2 or M4 is effected, then diagrams are obtained such forexample as those shown in Fig. 2. In both cases the distance was againM14 and the length of the transmitter dipole was M3. The spatial andelectrical lengths of the reflector dipole in the case of the diagram cwere M2.. In the case of the diagram at however the spatial length ofthe reflector dipole was M5 whilst in electric relation this dipole waselongated to M2. The elliptical diagram, 1. e., curve 0 has changed intoa cardioid. Spatial lengths between these values result in diagramswhich are between the two diagrams represented in the drawing.

The principle of the invention is applicable both to directivetransmitting and receiving arrangements. Further, each reflector dipolemay be replaced by several individual dipoles, arranged to actconjointly.

The arrangement represented in Fig. 3 is a. receiving arrangement whosedipoles M, RI, R2 are so-called half-dipoles and are tuned inconjunction with an electric or artificial earth E, that consists ofwire gauze or sheet metal, for instance. The centre dipole M is coupledto the receiver J by a coupling device K and is also tuned over thisdevice K. The reflector dipoles RI, R2 are tuned by means of aself-induction coil L which is common to them and is interposed in thesetwo dipoles alternately by means of a switch S. The coil L and the leadsQ to RI, R2 are contained in a screening P in order to avoid horizontalcomponents of radiation.

This arrangement has the advantage that only one tuning means has to bevaried for effecting the tuning to the proper wavelength. In the eventof an inaccurate tuning both reflectors RI, R2 will be detuned to thesame degree. The zone of equal field intensity, produced by connectingand disconnecting the reflectors alternately in a manner described inthe said patent, will then al- Ways be located in the plane of symmetry.Only the angle of intersection of the diagrams will undergo variation,because the shape of the directional diagrams depends upon the phase ofthe reflectors. Therefore, in the case of prior arrangements a diflerenttuning of the two reflectors causes the directional diagrams to be ofdifierent configuration and thus entails that the zones of equal fieldintensity will not be normal to the plane of symmetry. If however bothreflectors are always detuned to the same degree, as will be the case inarrangements according to Fig. 3, then, it is true, the shape of thediagrams and thus the angle of their intersection vary in conformitywith the degree of detum'ng, but the diagrams of RI, R2 remaincongruent,

that is to say, the zone of equal field intensity is.

in such case always normal to the plane of symmetry. The bearings hereobtained Will hence be faultless despite detuning. They will only beimpaired as regards their sharpness.

This arrangement is likewise adapted for use both on the transmittingand receiving sides of such systems. It will however be of peculiaradvantage when employed on the receiving side, because here thedirectional diagrams are difllcult to supervise.

What is claimed is:

1. A compact arrangement for directive wireless signaling comprising a,main antenna and two reflecting antennae cooperating therewith, thedistance between said reflecting antennae and saidmain antenna beingless than one-tenth wavelength and the spacial length of said reflectingantennae being shorter than the desired electrical length, means forelectrically elongating said reflecting antennae for tuning them to theoperative Wavelength and keying means for interposing said means forelongating alternately in said reflecting antennae.

2. A compact arrangement for directive wireless signaling comprising amain antenna, areflecting antenna arrangement comprising at least onereflecting antenna adapted to cooperate therewith, the distance betweensaid reflecting antenna and the main antenna being less than one-tenthwavelength, the spacial length of this reflecting antenna arrangementbeing shorter than the desired electrical length, means for electricallyelongating said reflecting antenna arrangement for tuning it to theoperative wavelength, an electric earth, the said reflecting antennaearrangement being tuned to a half wavelength in conjunction with thisearth, and a screening connected to such earth and encompassing the saidmeans for elongating said reflecting antenna arrangement.

3. A compact arrangement for directive Wireless signaling comprising amain antenna, reflecting antennae adapted to cooperate therewith, thedistance between said reflecting antennae and the main antenna beingless than one-tenth wavelength, the spacial length of these reflectingantennae being shorter than the desired electrical length, and means forelectrically elongating said reflecting antennae for tuning them to theoperative wavelength and keying means for rendering said reflectingantennae operative alternately to produce a desired intersecting field.

4. A compact arrangement for directive wireless signaling comprising amain antenna, a reflecting antenna adapted to cooperate therewith, thedistance between said reflecting antenna'and the main antenna being lessthan one-tenth wavelength, the spacial length of said reflecting antennabeing shorter than the desired electrical length thereof, and means forelectrically elongating said reflecting antenna for tuning it to theoperative wavelength, whereby a radiation pattern is produced differingmarkedly from the radiation pattern which would be produced if thespacial length of the reflecting antenna were as great as its electricallength.

5. A directive wireless signaling arrangement comprising a main antenna,reflecting antennae, each having a physical length shorter than thedesired electrical length and spaced from the main antenna less thanone-tenth of the operative wave length, means for electricallyelongating and tuning said reflecting antennae to said operative wavelength, and means for keying said reflecting antennae alternately tocause co,- operation thereof with the main antenna to produce a desiredintersecting field.

ERNST KRAMAR. HEINRICH BRUNSWIG.

